RESUMO
Objective@#To analyze the genetic characteristics of Coxsackievirus A4 isolated from Taian, 2017-2018.@*Methods@#Sixty throat swab samples of the children who visited Taian Maternal and Child Health Hospital during the year 2017-2018 and were diagnosed as hand, foot and mouth disease, were collected and aseptically inoculated. Fluorescent quantitative PCR analysis was performed using the universal primer for enteroviruses. The high-throughput sequencing was applied to the enterovirus-positive samples, and the full-length genome sequences of the viruses were obtained. Phylogenetic analysis was performed using Mega5.05 and RaxML respectively, and sequence homology and amino acid mutation sites were also analyzed using Mega5.05.@*Results@#Four whole genome sequences of CV-A4 isolated from infants aged 17-19 months old were obtained. Phylogenetic analysis of the full length CV-A4 genomes showed that apart from MG550920/AA/Henan/2016, the remaining CV-A4 strains from China (97.2%), including the four strains from Taian, fell within Group 3. The VP1 genes could be classified into four genotypes and 98.5% of the Chinese strains belonged to genotype D, and the four strains from Taian belonged to D2. It was notable that the Taian isolate A1/Taian is closely related to two strains C179 and C062 from Australia both in the complete genome and the VP1 gene, as well as one strain YT184R isolated from Yantai in 2016 by us. Compared with the prototype CV-A4 strain High Point, 18 amino acid mutations were found in the P1 region.@*Conclusions@#Both phylogenetic trees estimated using the complete genome and the VP1 gene sequences revealed that the four CV-A4 isolates from Taian fell within the same clade with the majority of CV-A4 strains circulating in China. Compared with the prototype CV-A4 strain, several amino acid variations have occurred in the P1 region, which warrants further investigation.